Subcontract Packing Slip (Crystal)

In Vista 803.408b the crystal report for Subcontract Packing slip is pulling the ship comment from the job BOM. i need to change it to pull the comments from the Purchase order comments. The comments might have had changes made to them in the PO. I am relatively new to crystal and I am having trouble finding the info to pull in. I have been able to alter it to the way I would like to view it but that is about all. I think I have to add another table but i don't know how to do that. any help would be appreciated.